The rotor of a wind power plant is usually supported in a main bearing which bears the rotor shaft. This shaft is provided for transmitting the output energy to an input shaft of a gear mechanism. The bearing of the rotor shaft is usually provided by means of a fixed/free-moving bearing system with at least two roller bearings. However, this design requires a large installation space and is relatively expensive.
Bearing arrangements of wind power plants in which only a single roller bearing is used as a bearing arrangement which can transmit all the forces and torques are already known. This solution is more cost-effective and takes up less installation space. For repair work on the main bearing or to change the bearing in a wind power plant it is generally necessary to remove the rotor. In view of the fact that more recent plants are installed on towers with heights over 100 m this is an enormous cost factor.
A bearing arrangement of this type is known, for example, from DE 101 02 255 A1. This document describes a wind power plant having a machine carrier which is to be attached to the top of a tower and which holds, on the one hand, the static part of an electric generator and, on the other hand, supports the rotating part of the latter as well as a hub of a rotor which bears rotor blades, wherein the rotor hub and the rotating generator part are attached to a common hollow shaft which is seated, by means of roller bearings, on an axle sleeve which is mounted on the machine carrier. There is provision here that a single bearing, which also takes up torques, is provided as the roller bearing means between the axle sleeve and the hollow shaft. This is claimed to reduce considerably the axial length of the axle sleeve and therefore its weight, and this also applies to the part of the hollow shaft which serves as the bearing system. In this context, the bearing is claimed to take up all the torques which also change in direction and which occur about axes which run transversely with respect to the axis of the shaft, without changing the relative position of the generator-rotor with respect to the generator-stator beyond a critical degree.
EP 1 426 639 A1 discloses a method for mounting a two-row tapered rolling bearing as a roller bearing of a wind power plant, which method is defined by the fact that the segments of a first internal ring and the segments of a second internal ring are positioned close to one another with their axial end sides facing one another, in such a way that at a time at which all the segments of the external ring just come to bear against the bore face and all the segments of the first and second internal ring just come to bear against the casing face of the shaft, an axial gap remains between the axial end faces of the segments of the first and second internal rings. Basically, the mounting of a segmented bearing is advantageous in terms of ease of mounting, but the division leads to virtually unavoidable inhomogeneity in the raceways of the roller bearing.
Finally, DE 103 51 524 A1 discloses an arrangement for transmitting rotor bending torques and rotor torques for a wind power plant which has a rotor hub with at least one rotor blade attached thereto as well as a large-diameter roller bearing which supports the rotor, said large-diameter roller bearing being, in particular, a tapered roller bearing with an external ring which is fixed to the housing and with a planetary gear mechanism which is connected downstream. In this arrangement there is provision for the hub to be connected directly to the internal ring of the radial bearing and/or to a bearing reinforcement ring. This is claimed to provide a particularly compact, lightweight and cost-effective arrangement for transmitting the rotor bending torques and torques via a large-diameter roller bearing and a gear mechanism.
All the solutions with a single main bearing of the rotor have the disadvantage that when it is necessary to replace the bearings this can only be done so with a large degree of expenditure in terms of machinery and work, and this is due in particular to the fact that the roller bearings have to be pulled off in the rearward direction, that is to say in the direction of the interior of the gondola of the wind power plant. This makes it necessary to open the gondola, remove claddings, and uninstall assemblies and machine components and the like which are in the way, which is a dangerous and particularly equipment-intensive activity at a height off the ground of up to 100 m since, under certain circumstances, several cranes and lifting platforms have to be used for this maintenance work.